|Raw Coke Warehouse|
|General information about the warehouse and product delivery to the factory||The raw material for the unit for calcining petroleum coke is the solid residue of the refining of crude petroleum coke. Coke to the territory of UPNK-PV LLP is delivered by rail and road, stored in a raw coke warehouse. The warehouse is a one-story building 150 meters long with 27 meter spans. The warehouse consists of eight sectors below the zero mark, allowing you to store a 10-day supply of raw materials. To move raw materials, the warehouse is equipped with two clamshell cranes with a lifting capacity of 10 tons each. There are two parallel lines for transportation and preparation of raw materials, consisting of vibratory feeders, crushers, conveyors, daily stock silos, bucket elevators, 3-hour stock silos and raw coke belt feeders.|
|Crusher (work process)||The crude petroleum coke warehouse is equipped with two crushers with a capacity of 70 t / h each. They are intended for grinding pieces of raw coke to sizes not exceeding 50 mm. Raw materials are supplied by means of a clamshell crane to a loading hopper equipped with a grate, the cells of which have a size of 255–255 mm. Thus, pieces of coke larger than 255 mm are not allowed on the crusher. From the hopper, coke is fed by means of a vibratory feeder to a gear two-roll crusher. Crushing tool - two rolls rotating towards each other. Teeth are located over the entire surface of the rolls, the gap between which, when reduced, is 50 mm. Smaller pieces wake up in the inter-roll space, and large pieces, respectively, undergo mechanical destruction.|
|Product path through a system of conveyors and elevators to a dosing hopper above the furnace||The crushed coke, after crushing through a system of belt conveyors and bucket elevators, falls onto a reversible belt conveyor designed to distribute crude petroleum coke between 4 silos of a daily supply of 250 tons each. Conveyors are equipped with magnetic separators for trapping metal particles and suction units for trapping coke dust.
From silos of daily supply, crude coke through a system of conveyor belts and bucket elevators is transported to bunkers of a 3-hour supply, from which it is fed to the calcination furnace.
|General information about the furnace. Role.||Calcination of petroleum coke is the process of heating crude petroleum coke to 1250-1350 ° C. At the same time, structural changes take place throughout the coke mass with the removal of hydrogen, which is released and burned in the form of methane and other hydrocarbon compounds in calcination and afterburning furnaces.The main purpose of the calcination process is to improve the physical and chemical properties of coke, such as electrical resistance, true density, oxidizability and reactivity, as a result, the product acquires the necessary qualities.|
|Dosing hopper and dispenser||Before getting into the calcination furnace, the raw coke enters the 60-ton metal 3-hour supply bin, which is installed directly above the loading end of the rotary calcination furnace.
Below, the hopper is equipped with a regulating valve, a needle gate and a belt feeder. From the feeder, the material is poured into a permanent drive equipped with a flap valve, due to which a certain amount of coke is accumulated and a metered supply of raw materials to the charging heat of the calcination furnace is performed.
|Calcining process||Coke is calcined in a rotary kiln with a length of 65 m and a diameter of 3.47 m, which is installed at an angle of 4 ° to the horizon and is able to rotate at a speed of up to two revolutions per minute. Due to the tilt, the rotation of the furnace facilitates the movement of coke from the loading end to the unloading end. The calcination furnace operates on the principle of countercurrent flow - crude petroleum coke is supplied from one side, and fuel is burned from the opposite. As a result, the gases formed during fuel combustion move towards the material flow, carrying out the heat exchange process directly. Fans of secondary and tertiary vodokha constantly supply air to the calcination furnace to ensure complete combustion of volatile substances. The combustion of volatile substances and fuel during the calcination of petroleum coke produces a large amount of high-temperature flue gases, which contain volatile substances and a small fraction of small particles of coke. 50-60% of volatile substances are burned in the calcination furnace, the rest enters the afterburning furnace along with flue gases. After evaporation of moisture and removal of volatile components, the coke is heated to 1350 ° C. Moreover, its molecular structure takes a more organized form with a clear crystal lattice. Due to the physical and chemical processes that occur with the raw material, there is an improvement in the consumer properties of coke. The full cycle of coke calcination from loading to unloading is at least 45 minutes.|
|Burner||The burner is located in the head of the furnace and is designed to ignite, dry and maintain a stable flame. The ignition of the calcination furnace is carried out using a fuel oil-diesel burner. Fuel oil is used as the main fuel in furnaces. To ignite and raise the temperature on the hot edge of the calcination furnace above 350 ° C, diesel fuel is used.|
|Refrigerator||The calcined coke refrigerator is designed to cool the calcined coke to a temperature of not more than 100 ° C, by direct irrigation with water,. Calcined coke, leaving the furnace through the discharge head, enters a rotating drum cooler. To move the material from the loading end to the discharge end, the refrigerator body has a slope of 2 ° 29 ’to the horizon. The steam generated during the cooling process of the coke is captured and sent to the afterburner, after passing through a cyclone dust collector to precipitate small particles of calcined coke. Coke particles captured on a cyclone are fed to the conveyor belt of the finished product.
Cooled coke, leaving the refrigerator, is conveyed through conveyor belts to a silo warehouse for the storage of finished products.
|Warehouse of calcined coke|
|general information||The calcined coke warehouse consists of four storage silos for finished products with a capacity of 1800 tons each, a system of belt and reversing conveyors equipped with magnetic separators and suction units.|
|Conveyor system, reversible conveyor||The conveyor system is designed to transport calcined coke to a finished product silo. Cooled coke is poured from the refrigerator onto conveyor belts. The place of filling is equipped with a flap valve, for dosed supply of material. The conveyors are equipped with magnetic separators to remove metal particles. At the next filling, by means of an electric three-way gate, the calcined coke is distributed between two parallel conveyors. In case of inconsistency of calcined coke with the required characteristics, it is possible to dump material on a specially equipped concrete site. Good material in the gallery is fed to reversible conveyors for distributing calcined coke between storage silos of the finished product. The calcined coke conveyor system is designed in such a way that allows simultaneous transportation of calcined coke of different grades without mixing.|
|Silos PNK loading in the railway carriage||The finished product silo warehouse consists of 4 silos with a capacity of 1800 tons each. To determine the filling level, each silo is equipped with radar level gauges. For convenient unloading of calcined coke, each silo has four discharge cones, consisting of a manual slide gate valve, a vibrating feeder, and a telescopic unloading device. Railways were laid under the silos to drive open gondola cars and load calcined coke into them. If necessary, it is also possible to organize the loading and export of calcined coke by road.|
|Heat Recovery Department|
|general information||In the process of calcining petroleum coke, a huge amount of heat is generated. Thermal energy is used to produce water vapor in waste heat boilers. The steam produced by the waste heat boilers is mainly used to generate electricity, as well as to meet the plant's own needs. The steam generating capacity of each waste heat boiler is 35 tons per hour. With the exception of the load on production and own needs up to 6 tons per hour, the total steam consumption for electricity production is 54 - 64 tons per hour. Utilization of flue gas heat is a process that allows you to cool the flue gas emitted into the atmosphere and receive electrical energy.|
|Waste heat boiler||High-temperature flue gas from the afterburner at a temperature of about 940 ° C is sent to the recovery boiler through a chimney. The recovery boiler is designed to recover flue gas heat and produce superheated steam. Feed water, after heating and degassing in an atmospheric deaerator, is fed by feed pumps to the water economizer of the recovery boiler where it starts heating. Water economizer consists of I and II stages.
From the water economizer, the feed water enters the upper drum of the boiler. The design of the drum provides a uniform distribution of feed water along its entire length.
Boiler water from the upper drum through the screen pipes of the cold part of the recovery boiler enters the lower drum of the recovery boiler, where water is mixed. Then, on the screens of the hot part of the recovery boiler, the steam-water mixture, passing the evaporative part of the boiler, rises into the upper drum due to natural circulation. Drum cyclones are installed inside the upper drum, where the separation process takes place - the process of separation of saturated steam from water.
Saturated steam through the steam pipes enters the input manifold of the first stage of the superheater. Having passed the coils of the superheater of the first stage, the steam enters the desuperheater, in which, if necessary, the temperature of the steam is lowered by injecting feed water. From the desuperheater, steam enters the input manifold of the second-stage superheater, passing coils of superheated steam with parameters P = 2.45 MPa and t = 400 ° C enters the output manifold of the superheater of the second stage, then the steam passes through the main steam valve through the steam line to the turbine compartment.
|Flue gas cleaning department|
|general information||The flue gas cleaning system consists of a bag filter, a cooling column and a desulfurization column. The main function of this system is the cleaning of flue gas from unburned coke dust and sulfur dioxide. Chimney gas, cooled and free of harmful substances, is emitted through the chimney into the atmosphere.|
|Bag filter||Bag filters, which are one of the most effective mechanical cleaning devices, are used to clean exhaust gases from mechanical impurities. The flue gases from the waste heat boiler pass through the flue to the central part of the bag filter installation, divided by a diagonal partition into two zones of dirty and purified gas. The untreated gases are evenly distributed over the compartments with filter elements equipped with a pulse cleaning system. Passing bag filters through the outlet dampers, flue gases enter the cleaned gas zone, from which they enter the suction ducts of the smoke exhausters.|
|Desulfurization Columns||When crude petroleum coke is calcined in rotary kilns, a large amount of volatile flue gases with a high content of sulfur oxide (SO2) is formed, which have an adverse effect on the environment. The desulfurization system is designed to purify flue gases from sulfur dioxide. Primary cleaning and cooling of the flue gas takes place in the cooling column by spraying a solution of sodium hydroxide. The main processes for removing sulfur oxide from flue gas occur in a desulfurization column, where, as well as in the cooling column, a solution of sodium hydroxide is supplied by spraying. Two irrigation water zones are installed in the upper part of the column to improve the course of reactions and to prevent the ingress of residual aggressive solutions into the chimney.
The alkaline solution that has reacted with sulfur dioxide flows from the columns into the reduction and oxidation pool, where it is mixed with the lime solution and saturated with oxygen to form gypsum particles. Further, the resulting solution with gypsum particles is poured into a precipitation basin, where gypsum-containing mass is deposited.
|general information||In order to rationally use the steam produced in the recovery boiler, a turbine compartment is provided at the plant. In the turbine compartment, as steam power plants, there are four condensing type turbines with a rated power of 3000 kW each. In normal operation, all four turbines generate 12,000 kW. Electricity is enough for own consumption, its excess is planned to be realized.|
|Turbine||Condensing steam turbines are used to convert the maximum possible part of the heat of steam into mechanical work. The unit consists of a turbine and a generator. Steam from the waste heat boiler enters the curved blades fixed around the circumference of the rotor, and acting on them, causes the rotor to rotate. The kinetic energy of the rotor rotation is transmitted to the reduction device. The shaft of the reduction device connected by means of a rigid coupling rotates the shaft of the generator. A rotating generator in turn generates electrical energy. Each steam power plant has a rated power of 3000 kW. The waste steam is sent to a condenser in which a negative pressure is maintained. Having passed into a liquid state, it is pumped out of the condenser in the form of water to a deaerator.|
|general information||To provide the plant with water, the parameters of which correspond to the requirements of the plants, a water desalination station is provided. River water is used as untreated water; its parameters, including turbidity, suspended solids, iron, manganese, and others exceed the permissible values. The cleaning system allows to reduce the parameters of process water to the maximum permissible values. Also, to reduce the oxygen content in the boiler water, two deaerators are used in the desalination unit.
|Desalination system||The water desalination system consists of sequentially arranged sand, carbon, cationic and anionic filters. The sand filter is used to remove iron ions, manganese ions, sediment, mechanical impurities and suspended particles from untreated water. A carbon sorption filter is used to form colloidal particles and form a coarse microphase, followed by precipitation. The cation exchange filter is filled with a filter element in the form of granules of a cation exchange resin. Its function is to replace the largest number of positively charged cations, such as potassium, calcium, sodium, iron, magnesium ions and others contained in water, with hydrogen ions H +. The anion exchange filter is filled with a filter element in the form of granules of anion exchange resin. Its function is to replace the negatively charged anions contained in water with hydroxide - OH- ions.|
|Deaerator||The desalination unit uses two rotor-film deaerators with a throughput of 50 tons per hour each. They work in parallel to meet the needs of production in boiler water. The presence of oxygen in boiler water can damage the equipment through corrosion. Therefore, make-up boiler water and a mixture of demineralized water with steam condensate from the turbine compartment are recovered in a thermal deaerator to prevent corrosion of the boilers and pipelines by oxygen molecules. In the deaerator, trickles of water move downward towards the steam coming from the steam distribution chamber, and in contact with it, are heated to the boiling point, as a result of which the oxygen dissolved in it is released from the water. The deaeration process takes place under a pressure of 0.12 MPa and a temperature of 104 ° C. Evaporated water and oxygen through the nozzle are sent to a heat exchanger to heat the water entering the deaerator. After removing oxygen, water is sent to the waste heat boilers to produce steam.|